The most common use for electrical conduit connectors is to facilitate the connection of a conduit or cable to a junction box. The junction box can be a variety of electrical enclosures such as an outlet box, transformer enclosure, circuit panel, lighting fixture—the list is nearly endless. Similarly, the conduit can be rigid or flexible, or could be hose, other tubing capable of routing electrical wire, or cable. Cable can be non-metallic sheathed cable, portable cord, or a variety of other types of electrical conductors. The instant invention is equally successful in connecting a plurality of types of conduits, cables, and other electrical conductors to a wide variety of boxes and other enclosures. Therefore, as used in this specification, the term conduit is not limited to standard rigid electrical conduit, but shall be intended to mean any type of conduit, any type of cable, or any other type of electrical conductor. Many commercial and residential buildings have electrical installations with many types of conduit-to-junction-box connections that utilize electrical connectors.
The two most common types of electrical connectors used are a snap-in connector, and a multipart connector which may be composed of two or more components that utilizes a threaded male end in conjunction with a threaded female locknut, hereinafter referred to collectively as a two-part locknut connector, without intent to limit such connectors to two parts only. In the case of the two-part locknut connector, the male threaded end is inserted into the junction box through a knockout. A rigid connection is established by threading the lock nut onto the male end in the junction box interior. The snap-in connector is another commonly used connector which utilizes a snap ring to quickly connect it to the junction box. Either type of connector is integrated with an adapter end which allows the attachment of conduit, cable, or a variety of types of hollow tubing.
The installation of electrical systems is generally expensive as an electrician must first install the enclosures, route conduit between each enclosure, and install connectors and then pull all necessary electrical wiring through the conduit. In other words, installation is expensive because it is labor intensive. The commercially available electrical connectors are one factor accentuating the labor intensiveness. Two-part locknut connectors increase the cost of installing electrical systems for a number of reasons.
The current art two-part locknut connectors are plagued with labor intensive problems. First, the two-part locknut connectors are shipped from the manufacturer preassembled. That is, the electrician must first remove the locknut from the male end before it can be installed. Once the male end of the connector is placed through the knockout, the electrician must rethread the locknut onto the connector from the interior of the junction box. Two hands are required to disassemble and then reassemble the connectors in the knockout. Consequently, it is difficult to hold a tool or a piece of conduit while reassembling the connector. Once the locknut is threaded it must be tightened. In accordance with many building codes and safety regulations, connectors must be firmly and reliably attached to junction boxes. To properly tighten the two-part locknut connector, the electrician must use a tool, usually a set of pliers or a screwdriver. Occasionally, when the proper tool is unavailable, an electrician will use any object within reach. These situations, while rare, raise serious safety issues. In many instances, however, to “get the job done” the locknut is “finger” tightened. Those persons skilled in the art know that finger tightened two-part locknut connectors can eventually loosen, and a loose connector can cause great strain to be put onto the electrical wires and their connections resulting in an increase in the probability of an electrical fire or other electrical problems, such as poor grounding.
Secondly, when the electrician disassembles the fitting by taking the locknut off the connector, the locknut can be dropped or misplaced. This can occur when the electrician is in an elevated position, such as, on a scissor lift or on scaffolding because electrical conduit is often installed in out-of-the-way places like in rafters and above ceilings. If the locknut cannot be found, the connector is useless. If the electrician decides to retrieve the dropped locknut, the installation time is prolonged.
A third common problem with the present two-part locknut connectors is the locknut is easily cross threaded onto the male thread. When this occurs, the electrician must usually use a tool to remove the locknut. On occasion, cross threading the locknut will damage the male threads on the connector making it difficult or impossible to reuse the connector. Again, the electrician must spend their time either removing the defective connector or forcing the locknut through the damaged portion of the threads.
A fourth problem with the present two-part locknut connectors is the distance the male end protrudes into the junction box. In some installations, the space inside the enclosure is already minimal. The space limitation becomes an acute problem when an additional connector is installed. The male threaded end protrudes well past the depth of the locknut and may interfere with another connector, the contents of the enclosure, or wiring inside the box. Therefore, in a limited space enclosure, the excess thread must be removed. Typically, the electrician saws off the excess thread, or may clip off some of the receptacle or mounting screws, or completes a combination of space enlarging modifications, all of which prolong installation time and threaten the integrity of the system as designed.
A fifth common problem with the present two-part locknut connectors occurs during disassembly of the connector from the enclosure. Electricians may disassemble an installation for a variety of reasons. The disassembly of the two-part locknut connector is more time consuming than the installation. If the locknut was installed properly, that is, by tightening it with a tool, then the locknut must be removed with a tool. Similar to the installation, if the threads are damaged during disassembly, the connector is useless. Also similar to the installation problems, if the locknut is lost, it must be replaced if the connector is to be used again. If the connector was “modified” during installation because space inside the enclosure was limited, disassembly may be exceedingly difficult or impossible due to the probability that the threads on the male connector have been damaged.
The snap-in connector presents similar problems. However, the most significant problem is that these connectors, in most cases, do not create a rigid connection. Because the snap ring is sized to accept a variety of box wall thickness, it does not rigidly attach to many boxes. The loose fit may cause electrical continuity problems, a highly dangerous situation, since the box, the conduit, and the connector are intended to be part of the electrical grounding system in some applications.
Another problem with the snap ring devices is that they are inherently not liquid tight. As is commonly known in the industry, liquid tight refers to the connector's propensity to prohibit liquids from penetrating through the connector and into the junction box. Many applications require the connections of the conduit to the electrical enclosures to be impervious to any liquids found in the surrounding environment, whether the liquid is water, hydraulic fluid, or any other fluid found in industry. In these applications, liquid tight connectors are required for safety purposes, specifically to avoid electrocuting those nearby and to avoid fire. Since, as stated previously, the snap-in connectors do not create a rigid connection, they cannot be confidently utilized in liquid tight applications.
There remains an unfulfilled need to provide a generally universal connector which can be installed quickly and easily without tools, does not require access to the interior of the junction box, and does not need to be disassembled before connecting it to an electrical enclosure. Additionally, there remains an unfulfilled need to provide a generally universal connector providing a rigid; and where required by code, an electrically conductive connection; conserves space within the enclosure; and can be made to be liquid tight.